Four astronauts aboard the International Space Station readied their SpaceX Crew Dragon capsule for undocking Saturday night, setting up a fiery plunge to a pre-dawn splashdown in the Gulf of Mexico Sunday to close out the first operational flight of SpaceX’s futuristic touch-screen ferry ship. Crew-1 commander Michael Hopkins, along with NASA astronauts Victor Glover and Shannon Walker and Japanese astronaut Soichi Noguchi, planned to undock from the space-facing port of the station’s forward Harmony module at 8:35 p.m. EDT, setting up a splashdown in the Gulf south of Panama City, Florida, at about 2:57 a.m. Sunday. The Crew Dragon’s return to Earth will mark only the second piloted water landing since SpaceX began launching astronauts last year in NASA’s commercial crew program and just the third night splashdown in space history — the first in nearly 45 years. Crew-1 astronauts Shannon Walker, Victor Glover, Michael Hopkins and Soichi Noguchi, pictured here floating in the space station’s Destiny lab module, will wrap up a 168-day stay in orbit with a pre-dawn splashdown Sunday in the Gulf of Mexico. NASA SpaceX crews were stationed Saturday in the landing zone to secure the Crew Dragon, haul it on board a company recovery ship and help the astronauts out of the spacecraft on stretchers, as they begin re-adjusting to gravity after five-and-a-half months in weightlessness. Following medical checks and phone calls home to friends and family, all four crew members are to be flown to shore by helicopter and handed off to NASA personnel for a flight back to the Johnson Space Center in Houston. While mission managers prefer daylight landings, rough weather ruled out re-entry plans Wednesday and Saturday. With mild winds expected early Sunday, NASA and SpaceX agreed to target a pre-dawn return for the Crew-1 astronauts. Unlike the first piloted Crew Dragon splashdown last August, when the spacecraft was quickly surrounded by boaters enjoying a sunny Sunday afternoon in the Gulf, the Coast Guard planned to enforce a 10-mile-wide safety zone for this landing to keep any early morning onlookers well away. The Crew Dragon’s return will complete a record-pace crew rotation requiring two launches and two landings with four different spacecraft over just three weeks to replace the International Space Station’s entire seven-member crew. The first Crew Dragon splashdown came last August when astronauts Douglas Hurley and Roberrt Behnken landed in the Gulf of Mexico after the first piloted flight of the SpaceX capsule. NASA On April 9, a Russian Soyuz spacecraft carried Oleg Novitskiy, Pyotr Dubrov and NASA astronaut Mark Vande Hei to the station after a launch from the Baikonur Cosmodrome in Kazakhstan. They replaced another Soyuz crew — Sergei Ryzhikov, Sergey Kud-Sverchkov and Kate Rubins — who returned to Earth on April 17. Then, on April 24, a Crew Dragon brought Crew-2 commander Shane Kimbrough, NASA astronaut Megan McArthur, European Space Agency astronaut Thomas Pesquet and Japanese flier Akihiko Hoshide to the station. The first stage of the Falcon 9 rocket that launched them the day before also helped launch Hopkins and company, the crew they are replacing aboard the station. After helping the Crew-2 astronauts settle in aboard the lab complex, Hopkins, Glover, Walker and Noguchi, who arrived at the station last November 16, planned to bid its seven crew members farewell Saturday evening, floating into their own Crew Dragon for undocking. After moving a safe distance away, the ship’s flight computer is programmed to fire the ship’s braking thrusters for about 16-and-a-half minutes starting at 2:03 a.m. Sunday. Moving through space at more than 17,100 mph — more than 83 football fields per second — the rocket firing is designed to slow the Crew Dragon by just 258 mph or so, just enough to drop the far side of the orbit into the dense lower atmosphere on a path targeting the Gulf of Mexico landing zone. Protected by a high-tech heat shield, the Crew Dragon is expected to slam into the discernible atmosphere around 2:45 a.m., rapidly decelerating in a blaze of atmospheric friction. Once out of the plasma heating zone, the spacecraft’s parachutes are to unfurl, allowing the ship to settle to a relatively gentle impact in the Gulf. The most recent previous nighttime water landing came in October 1976 when two cosmonauts in a Soviet-era Soyuz spacecraft, making an unplanned descent in blizzard-like conditions after a failed docking, were blown off course into a large lake in Kazakhstan. It took recovery crews nine hours to move the spacecraft to shore and rescue the cosmonauts. The only other night splashdown came in December 1968 when the crew of Apollo 8, coming home from a Christmas trip around the moon, carried out a planned, uneventful pre-dawn landing in the Pacific Ocean.